1. Field of the Invention
The present invention relates to a lubricant supplying device, an image forming apparatus, and a process cartridge.
2. Description of the Related Art
In image forming apparatuses such as printers, facsimiles, and copying machines, it is known that, for the protection of and lowering the friction of an image carrier such as a photosensitive element and an intermediate transfer belt, some apparatuses are provided with a lubricant supplying device that supplies lubricant to the surface of the image carrier.
In image forming apparatuses such as printers, facsimiles, and copying machines, it is known that, to protect and to lower the friction of an image carrier such as a photosensitive element and an intermediate transfer belt as a lubricant supplying target, some apparatuses are provided with a lubricant supplying device that supplies lubricant to the surface of the image carrier.
A lubricant supplying device includes a supplying member that abuts a bar-shaped solid lubricant to rub off lubricant and supplies the lubricant in fine powder to an image carrier. The lubricant supplying device further includes a lubricant retaining member that retains the solid lubricant at the portion on the side opposite to the side that abuts the supplying member. The lubricant retaining member is housed in a case of the lubricant supplying device to be movable in a contacting and separating direction of the solid lubricant with respect to the supplying member. Furthermore, in a space on the side opposite to the side of the lubricant retaining member that retains the solid lubricant inside the case, a pressing mechanism that presses the lubricant retaining member on the side opposite to the side that retains the solid lubricant towards the supplying member.
When the supplying member rotates, the solid lubricant abutting thereon is rubbed, and the lubricant rubbed off and adhered onto the supplying member is applied to the surface of the image carrier. The solid lubricant is gradually scraped off by rubbing of the supplying member, and the lubricant retaining member moves towards the supplying member. The solid lubricant abuts the supplying member from the beginning to the end of use; and thus, the solid lubricant can be scraped off favorably by the supplying member.
When image forming operation is performed while the lubricant is exhausted, as the protective action of the lubricant is not exercised, the image carrier is worn and is deteriorated. In Japanese Patent Application Laid-open No. 2011-197126, disclosed is a lubricant supplying device including a remaining amount detecting unit that detects the length of the solid lubricant in a moving direction thereof (hereinafter, referred to as a height of the solid lubricant) to be at a given value or less while being scraped off by the supplying member so as to detect that the remaining amount of lubricant is so small.
The lubricant supplying device disclosed in Japanese Patent Application Laid-open No. 2011-197126 is provided with an electrode member in a lateral direction of the solid lubricant (a moving direction of the surface of the supplying member at an abutting portion between the solid lubricant and the supplying member) as a remaining amount detecting unit, and when the remaining amount of lubricant becomes so small, the electrode member and the conductive lubricant retaining member abut each other and become a conductive state from a non-conductive state. Accordingly, becoming a conductive state from a non-conductive state detects the remaining amount of lubricant being so small.
In the lubricant supplying device disclosed in Japanese Patent Application Laid-open No. 2011-197126, however, it is found that the electrode member and the lubricant retaining member sometimes do not make contact with each other, even when the remaining amount of lubricant of the solid lubricant becomes so small, causing an erroneous detection.
In view of the above-described situation, there is a need to provide a lubricant supplying device, an image forming apparatus, and a process cartridge that can prevent an erroneous detection of the remaining amount detecting unit.
The applicants have identified the following as a result of their devoted studies on the root cause of the electrode member and the lubricant retaining member not making contact with each other causing an erroneous detection even when the remaining amount of lubricant of the solid lubricant becomes so small. More specifically, it is found that, when the electrode member as the remaining amount detecting unit is arranged on the upstream side in a rubbing direction of the supplying member with respect to the solid lubricant, the electrode member and the lubricant retaining member do not make contact with each other causing an erroneous detection. The solid lubricant receives force towards the downstream side in the rubbing direction of the supplying member at the portion abutting the supplying member. When the solid lubricant receives force towards the downstream side in the rubbing direction by rubbing of the supplying member, the lubricant retaining member moves towards the downstream side in the rubbing direction of the supplying member with respect to the solid lubricant. As a result, when the electrode member as the remaining amount detecting unit is provided on the upstream side in the rubbing direction of the supplying member with respect to the solid lubricant, the electrode member and the lubricant retaining member do not make contact with each other even when the remaining amount of lubricant of the solid lubricant becomes so small, thereby causing an erroneous detection.
While a failure caused by using the remaining amount detecting unit that detects electrical conduction between the electrode member and the lubricant retaining member being provided on the upstream side in the rubbing direction of the supplying member with respect to the solid lubricant is explained in the foregoing, it is not limited to this. For example, even with a lubricant supplying device that includes a remaining amount detecting unit that detects the remaining amount by a detected portion pressing a push switch when the remaining amount of lubricant comes to a near end, when the push switch as a remaining amount detecting unit is arranged on the upstream side in the rubbing direction of the supplying member with respect to the solid lubricant, the detected portion does not make contact with the push switch causing the same failure as that in the foregoing. Furthermore, even with a lubricant supplying device that includes a remaining amount detecting unit that detects the remaining amount by a detected portion that faces a photo interrupter when the remaining amount of lubricant comes to a near end, when the photo interrupter is arranged on the upstream side in the rubbing direction of the supplying member with respect to the solid lubricant, the detected portion does not face the photo interrupter causing the same failure as that in the foregoing.